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NASA’s Dawn spacecraft, which orbited the asteroid Vesta in 2012, produced intriguing images of gullies on the asteroid’s surface, prompting scientists to investigate their formation. Vesta, primarily recognized for its craters, also showcases channels that challenge the expectations set by the extreme conditions of space. A recent study suggests that these features may result from transient flows of liquid, potentially linked to briny water. Laboratory experiments have been conducted to recreate the conditions on Vesta, providing insights into this previously unverified process.
Simulating Vesta’s Environment
The study, published in the Planetary Science Journal, details the research spearheaded by scientists at NASA’s Jet Propulsion Laboratory (JPL). To mimic Vesta’s environment, the team employed the Dirty Under-vacuum Simulation Testbed for Icy Environments (DUSTIE) to simulate conditions following impacts from meteoroids. Findings from these experiments indicated that while pure water ice forms quickly in a vacuum, salty liquids can remain in a liquid state for extended durations. Michael J. Poston, lead author and researcher at the Southwest Research Institute, emphasized that briny solutions could persist as liquids for up to an hour, which is sufficient to form the observed gullies.
Brine Deposits as a Key Factor
This research posits that impacts on Vesta may unearth subsurface brine deposits, leading to momentary liquid flows before they freeze again. Jennifer Scully, a planetary scientist at JPL, explained that such impacts could initiate the release of liquid, which would be active long enough to etch surface structures. During discussions with reporters, Scully mentioned that the presence of frozen “lids” over brine could stabilize the underlying liquid, allowing it to flow for longer periods.
Insights Beyond Vesta
The implications of these findings extend beyond Vesta itself, aligning with observations from other celestial bodies like Mars and Europa, one of Jupiter’s moons, where similar liquid mechanisms may occur. Moreover, this research contributes to the body of evidence gathered during the Dawn mission, which suggested the existence of brines on Ceres, another object within the asteroid belt. Though the confirmation of frozen brine on Vesta remains to be achieved, these experimental insights open new avenues for understanding geological processes on celestial bodies lacking atmospheres.
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